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The Mystery of Protein Sensitive Hair: Solved

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Table of Contents

Find out if protein sensitive hair is a thing.

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In the curly hair community, we’re constantly exploring new avenues to enhance our hair care routines. The most recent topic buzzing within our community is the concept of protein sensitivity in hair.

Protein-sensitive hair, in essence, pertains to a condition where your hair does not react favorably to products infused with proteins. The manifestations of this sensitivity can vary, ranging from unruly frizz to stiffness. It’s important to note that the precise definition of protein sensitivity remains a subject of discussion within the curly hair community.

I’ve contacted my knowledgeable friend, who happens to be a hair scientist, to assist us with this topic. His expertise will guide us through the intricacies of protein-sensitive hair (we’ll clarify this concept shortly), allowing us to develop a thorough understanding of the subject.

What are Hair Proteins?

Image of the chemical structure of human hair.

Hair is a protein by nature, and this protein is called keratin. It constitutes about two-thirds of the mass of hair. The structure of keratin is helical, where two strands of protein chains are bonded together through various bonds.1

Hair proteins are primarily composed of amino acids, serving as the essential building blocks that underpin the structure and strength of our hair.1

When hair sustains damage, it can lead to raised cuticle scales with gaps and cracks along the hair shaft. Depending on the severity of damage, this may expose the fragile cortex beneath, resulting in weakened and brittle hair.2

Protein and Its Role in Hair Care

Proteins are a fundamental component of hair care products and regimens.3 They are often surrounded by misconceptions, with some believing they are exclusively meant for individuals with damaged hair (high porosity hair), fearing that their use might lead to stiffness or breakage.

In reality, hair proteins offer benefits to all hair types, including low-porosity hair.4 To clarify these misconceptions, let’s explore some key facts about proteins.

Diverse Proteins in Hair Care Formulations

In hair care formulations, it’s important to recognize that not all proteins listed in the ingredients list are identical.

These proteins possess distinct chemical structures and compositions, resulting in varying levels of affinity for the hair fiber.5

The key takeaway here is that not all hair care products are equal due to differences in their ingredient formulations.

To gain a deeper understanding of the importance of proteins for hair, I invite you to explore my blog titled, “Proteins for Curly Hair: A Comprehensive GuProteins for Curly Hair: Everything You Need to Know” and “Proteins for Hair: Facts and Misunderstandings.”

Understanding Protein’s Interaction with Hair: Size Matters

The interaction of protein molecules with your hair depends on factors such as their source, molecular weight, and size.3 This understanding is essential when choosing the right protein for your hair regimen.

Low molecular weight proteins (smaller protein fragments) are highly capable of penetrating deep within the hair strand, reaching the cortex.6 This also makes them particularly suitable for a deep conditioner or protein treatment.

They effectively strengthen the hair fiber and help recover protein loss caused by rigorous grooming, chemical treatments, etc.

In contrast, high molecular weight proteins tend to be absorbed onto the hair shaft’s surface, creating a protective coating.6 They excel in adhering to the cuticle layer, significantly enhancing the hair’s surface characteristics.

In the table below, you’ll find the average molecular weights of commonly used proteins.

Image of protein weight in dltons.

Signs of Incorrect Protein Usage in Your Hair Care

Several signs may suggest that you’ve chosen an inappropriate protein treatment for your hair, or that your hair may not have required protein at that moment:

  • Excessive Stiff Hair: Hair may feel overly rigid and stiff, often described as lacking flexibility or “crunchy” to the touch.
  • Dryness: Hair may become excessively dry hair and lack moisture, leading to a parched, straw-like texture.
  • Brittleness: Hair can become more prone to breakage and split ends, making it appear weak and damaged.
  • Lack of Shine: Hair may lose its natural luster and appear dull or lackluster.
  • Increased Frizz: Protein overload can lead to increased frizz and a lack of smoothness in the hair.
  • Tangly: Hair may become more tangled and difficult to manage.

It’s essential to pay attention to these symptoms and adjust your hair care routine accordingly to maintain healthy and balanced hair.

If you suspect protein overload or an incorrect choice of protein treatments, consider using lubricating and conditioning products to restore the hair’s moisture balance.

What are Protein Treatments?

Image of a magnified damaged hair cuticle with three protein treatments on top.

Protein treatments for hair involve the application of products containing proteins, often sourced from substances like silk protein, keratin, wheat, oat, soy protein, etc. The primary purpose of these treatments is to strengthen and temporarily repair the hair.

These treatments are particularly beneficial for hair that has undergone damage due to factors such as bleaching, heat styling, normal wear and tear, or exposure to the sun. They play a crucial role in enhancing the structural integrity of the hair.

Protein-based products work by filling in gaps and cracks along the hair shaft, effectively reducing breakage and promoting overall healthy hair.7

In doing so, they not only address existing damage but also serve as a preventive measure against further harm.

Tailoring Protein Treatments to Different Hair Types and Needs

In reality, all hair types can gain advantages from protein treatments. Whether your hair is damaged due to chemicals, heat, or regular wear and tear on the ends of your hair, incorporating a protein treatment can be beneficial.

For fine hair, smaller protein fragments are often the most suitable as they can effectively strengthen the hair without weighing it down.

On the other hand, coarse hair may not require protein treatments as frequently, as it typically possesses a robust structure.

Medium-textured hair falls somewhere in between, benefiting from a balanced approach to protein treatments based on its specific needs.

Hair Stiffness and Protein Interaction with Hair’s Chemical Bonds

image to represent hair bonds.

To understand the mechanical stiffness of hair as a result of protein application, we need to understand the chemical bonding inside keratin.

Salt Bonds

This bonding involves oppositely charged chemical groups of two peptide (protein) chains. These bonds can be broken by pH changes in the hair, in both the acid or alkaline direction. Readjusting the hair’s pH will reform and stabilize these bonds.8

Disulfide Bonds

This is the most important chemical bond present in hair structure and is responsible for the mechanical strength of hair.9 These bonds cannot be broken by water or heat manipulation.10

Only chemical agents can break these bonds,10 and if conditions return to normal, they can potentially reform, albeit possibly in a different configuration.

It is the main site of action for chemical treatments for permanent hair reshaping and styling.9,11

For example:

  • Perming
  • Hair straightening
  • Relaxing

Under alkaline conditions, disulfide linkages are converted to lanthionine bonds resulting in a permanent chemical change, which is a process generally used in permanent hair straightening.12

The higher in porosity your hair is, the weaker and/or fewer disulfide bonds are. Conversely, the lower in porosity your hair is, the more and/or tighter the disulfide bonds are.

Hydrogen Bonding

These are the most flexible bonds that are easily broken in the presence of water.13

When the hair is wet during washing or in the presence of a lot of humidity, water molecules enter and break apart these hydrogen bonds.1 The good thing is that they are easily changed back.

Hydrogen bonds allow the hair to change shape temporarily and produce a strong hold. (i.e., wet setting, roller sets).1 This explains why high humidity causes large frizz and hairstyling problems.

Protein treatments are designed to interact strongly with these chemical bonds. Proteins may act or react with hair via two strategies:6

  • Small molecules of protein enter the hair via cracks/holes in the cuticles, and they are firmly bound within.
  • While large protein molecules form a coating, creating a strong film along the hair shaft.

Why You Think You May Have Protein-Sensitive Hair

Infographic of reasons why you may think you have protein sensitive hair.

Let’s explore some potential reasons why your personal experience with protein may not have met your expectations.

You used the wrong protein for your hair type

Every person has a distinct type of hair fiber and texture. Some of us have had our hair chemically altered in some way, whether it be by perms, relaxers, or oxidative coloring.

Chemical treatments can make your hair highly porous and create gaps in its structure.14 If you use large protein molecules, they might not get inside the hair but instead stay on the surface, leaving the inner empty spaces untouched.6

The size of protein molecules in your hair product plays a pivotal role in determining whether it’s a good match for your hair. If the molecular size is not suitable for your hair type, you may mistakenly perceive your hair as protein-sensitive.

In simpler terms, using the wrong protein can be a problem.

So, what’s the solution?

We need small protein molecules that can go inside the hair and fill those gaps. If the proteins are too big, they might just sit on the surface and make your hair feel stiff and rigid.6

It’s important to understand this aspect of product selection, as choosing the right protein size can significantly impact the effectiveness of your hair care routine and help you achieve the best results for your unique hair needs.

Not Balancing Protein Usage

Products that have protein listed among the first 5 – 6 ingredients have a higher concentration of proteins.

Even those who do a lot for our curls may sometimes feel we need to strengthen our hair and can overdo it with protein.

It’s not so much that we have “protein-sensitive hair,” it’s just that we need to cut back on the frequency.

So, in this situation, do not use protein products as frequently. Keep in mind that applying three different products could mean putting ten or more protein ingredients on your strands.

As a result, it’s critical to understand the ingredients, but the product combination and quantity are also significant.

Protein overload

Another reason you may think you have protein-sensitive hair is using too much protein can lead to the accumulation of protein molecules on the hair’s surface. This buildup can also occur when using high molecular synthetic polymers.

The accumulation of protein on your hair’s surface can result in hair becoming hard to handle, losing its luster, and appearing lifeless.

When you continue to apply proteins repeatedly, this buildup persists and eventually causes your hair to become stiff and rigid.

If you have protein buildup, then use a clarifying shampoo, as it is important to remove protein and any polymeric buildup.15

However, it does not necessarily mean you need a sulfate shampoo, a good mild cleanser will do a great job.

This cleansing should be followed by emollients and moisturizing treatment to provide much-needed moisture to your hair.

It’s also a good idea to consider using protein-free products until your hair regains its balance.

Coarse Hair

Coarse hair, by its nature, is often more robust and less prone to damage than finer hair textures. As a result, it may not require protein treatments as frequently as other hair types.

This doesn’t necessarily mean you have a sensitivity to protein; rather, it reflects the unique needs of your coarse natural hair, which may benefit more from conditioning and lubricating treatments to maintain its health and manageability.

Protein-Moisture Imbalance

Failing to follow up an intense protein treatment with a deep conditioner can create a temporary imbalance in hair moisture and make the hair feel brittle or stiff.

This can lead some individuals to mistakenly perceive their hair as protein-sensitive when, in reality, it simply needs a proper moisture balance to regain its flexibility and softness.

Build up

Buildup in the hair can indeed make it feel stiff, and using a protein treatment on hair with buildup can exacerbate this sensation.

To address this issue, it’s essential to clarify your hair with a clarifying shampoo, essentially providing your hair with a “reboot” before considering protein treatments.

This helps remove the buildup and restore your hair’s balance, allowing protein treatments to work effectively and avoiding the misconception of protein sensitivity.

Timing is Off

Using proteins at the wrong time in your hair care routine can be a common factor leading to perceived protein sensitivity.

Timing matters because applying protein treatments when your hair doesn’t need them can lead to stiffness and imbalance.

It’s essential to assess your hair’s current condition and moisture-protein balance before deciding when to use protein-based products.

How To Prevent And Resolve “Protein Sensitive Hair

A sensitivity to protein might be indicated by an adverse reaction to it during or after application.

The problem is since there are so many ingredients in a product, how do you know which one is causing the problem?

It’s possible that it’s a mixture of ingredients that you’re sensitive to rather than the protein itself, but the only way to figure out what is causing the problem is through trial and error.

Everyone’s hair is unique and will react differently. But, what makes it more complicated is that not all proteins are the same.

So, before declaring yourself protein sensitive, think about the types of protein you apply to your hair, how often you apply them, and your hair’s current condition.

There are many types of proteins extracted from various sources.

For example:

  • Milk
  • Oats
  • Wheat
  • Rice
  • Quinoa
  • Soy
  • Keratin, etc.

These are all different in amino acids’ molecular weight, size, and chemical composition.5

The table below describes some of the protein for curly hair used in hair care products. It also tells us their amino acid profile (in percentage).

Please note: If you’re viewing this post on your mobile device, use your fingers to scroll the graph to the left in order to access all of the information.

Amino AcidHuman
Wheat ProteinSoyaRiceOat CollagenMilkSilkQuinoa
Alanine4.502.704.505.906.409.304.50 29.80 2.17
Arginine9. 3.02
Asparagine9.003.1012.309.208.606.307.30 1.17 3.69
Cysteine13.001.801.002.400.40 0.13
Isoleucine18.1036.8020.1020.4024.309.6020.60 0.41 8.75
Glycine5.603.504.504.608.8024.603.20 46.00 3.00
Histidine13.002.202.603.402.200.902.80 2.17
Isolucine2.403.403.805.002.601.604.40 0.33 0.82
Threonine4.607.307.409.107.503.307.20 0.17 2.48
Lysine3.601.706.403.704.103.807.30 2.35
Methionine0.801.501.302.101.801.002.40 0.31
Phenylalanine2.305.404.805.904.302.303.00 5.70 1.54
Proline9.3012.005.304.403.9013.6012.30 1.82
Serine13.105.705.404.905.103.007.7011.45 1.66
Theronine9.102.904.103.703.402.005.10 1.12 5.71
Tryptophan1.201.50 1.03
Tyrosine0.800.903.602.000.900.303.30 1.66 1.20
Valine5.204.104.706.903.903.205.70 2.19 0.99
Table 1: Amino acid profile of various proteins. The data is an average of multiple data sets.3,16

Proteins that contain high levels of glutamic and aspartic acids are better for hair conditioning, moisturizing, and hydration (for example, wheat and oat protein).17

Human hair keratin is rich in sulfur-containing cysteine, which provides hair strengthening and improves its tensile properties.1


Protein treatments play a vital role in maintaining healthy hair by strengthening the hair shaft and improving its moisture retention capacity. Achieving a balance between protein and moisture is crucial since water molecules bind effectively to a well-structured protein within the hair shaft.18

However, it’s essential to understand your hair’s unique needs. Indiscriminately applying various protein products isn’t the solution. Excessive protein use can actually harm your hair. Instead, choose the right type of protein that suits your hair type and condition.

Carefully reading product labels is crucial. Keep track of how your hair responds to different ingredients, both positively and negatively. You are the best judge of what works best for your hair, so pay attention to its specific requirements.

As I always, say, let your hair be your guide!


Is coconut oil bad for protein-sensitive hair?

There is no definitive concept of “protein-sensitive hair.” However, coconut oil is typically safe to use for most individuals, as it’s considered a non-protein emollient.19

It can provide moisture and conditioning benefits without contributing to protein overload. However, individual reactions, including the possibility of allergic reactions, can vary.

Therefore, it’s advisable to conduct a patch test or consult a hair care professional if you have any concerns.



I’m just a girl who transformed her severely damaged hair into healthy hair. I adore the simplicity of a simple hair care routine, the richness of diverse textures, and the joy of sharing my journey from the comfort of my space.

My mission? To empower others with the tools to restore, and maintain healthy hair, and celebrate the hair they were born with!

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